How much battery storage do you need to power your home? In this guide, we explore some of the most common scenarios for UK households.
Are you contemplating the installation of a storage battery but find yourself uncertain about the appropriate size for your needs?
Determining the ideal size typically hinges on several key factors: the specifications of your solar panels, your household's energy consumption patterns, and your specific objectives.
Within this guide, we'll review some of the most common scenarios and provide insights on how to accurately assess the required size, accompanied by recommendations for suitable products.
PS We offer MCS-certified battery installation nationwide. Simply answer these questions, get your fixed price and arrange your free design.
How Much Battery Storage Do You Need?
Battery Size Vs Dimensions
Before looking at the calculations, it's crucial to establish a clear understanding of what constitutes a battery's size. This term can encompass either its total capacity, measured in kilowatt-hours (kWh), or its physical dimensions.
While it's often assumed that larger batteries boast higher capacities, this isn't universally true. Therefore, it's imperative to verify the capacity of the specific battery under consideration.
For this guide, when we mention "size," we're primarily referring to the various aspects related to its energy storage capabilities, such as maximum capacity and usable capacity, quantified in kilowatt-hours (kWh).
Now that we've clarified this distinction, let's explore solar battery sizes and their relevance to your household's energy consumption.
How To Size Your Solar Battery
Solar batteries serve the crucial function of storing surplus energy generated by your solar system, which would otherwise be directed back to the grid.
For those equipped with a smart meter, an added advantage emerges: the ability to charge your solar battery from the grid during off-peak hours, typically occurring overnight when energy costs are lower. The capacity of solar batteries is quantified in kilowatt-hours (kWh).
As a convenient aid, refer to the table below for a quick estimation of the battery capacity required based on your annual energy consumption.
To ascertain your annual energy consumption, simply consult your previous energy bills.
Explore potential savings through our complimentary smart draw tool, accessible here.
Annual energy consumption (KWh) | Number of Panels | Battery Capacity Required |
2500 | 8 | 5-7 KWh |
3500 | 10 | 8-10 KWh |
5000 | 14 | 11-16 KWh |
For a more accurate calculation, you need to know the daily average for three things:
The amount of energy in KWh, your solar system is estimated to produce
The amount of energy generated you’re expected to export to the grid KWh
How much energy you use per day in KWh
All of this information will be provided to you with your MCS proposal. If you don’t have that to hand, you can use our online solar tool here to see how much different batteries can potentially save you.
Once you have that, use this formula:
Daily average consumption – daily average generation + daily exported energy + 35%
This will get you a big enough battery to size your system, plus some redundancy to charge it from the grid in the winter months when solar generation is lower.
Battery Specifications - What Else Is Important?
When specifying a battery, you’ll need to consider both the battery capacity (measured in KWh) and the battery charge and discharge rate (measured in KWs).
If you think of a battery like a bathtub, the capacity of the battery would be the amount of water it can hold, and the charge and discharge rate would be how fast it can fill and drain.
A general rule is to avoid batteries with low charge and discharge rates under 3KW.
Recommended Solar Batteries
Here is a list of some of our favourite solar batteries with their capacity, charge/discharge rates, warranty and estimated prices:
Brand | Model | Capacity (KWh) | Charge/Discharge rate (KW) | Warranty | Price (estimated) |
Tesla | Powerwall 2 | 13.5 | 5 | 10 years | £6995 |
Tesla | Powerwall 3 | 13.5 | 11.1 | 10 years | £7395 |
Alpha | Smile 5 | 11.4 | 5 | 5 years | £3895 |
Alpha | G5 | 10.1 | 5 | 10 years | £4245 |
Enphase | IQ Battery 5P | 5.0 | 3.24 | 15 years | £2875 |
Table last updated: April 2024.
Why Is Choosing The Right Size Battery Important?
Selecting the appropriate battery capacity for your home and objectives is pivotal to ensuring you can store enough energy to fulfil your needs.
Typically, erring on the side of a larger capacity is recommended for added security. However, opting for a capacity that surpasses your requirements may result in unnecessary expenditure.
Should you opt for a capacity that proves too modest, expansion remains a viable option by integrating additional batteries. Nonetheless, it's imperative to verify that the chosen battery is stackable, as not all brands offer this feature.
For instance, consider the Alpha Smile B 3 range, renowned for its modular design, allowing seamless expansion. With the Smile B3 5.02kWh model serving as a foundation, you can incorporate up to five additional 5.02kWh modules, offering versatility for evolving needs. This system can expand to a maximum capacity of 30.24 kWh, accommodating growing families or individuals seeking flexibility.
Additionally, consider factors like depth of discharge (DoD), denoting the proportion of a battery's rated capacity withdrawn during usage, and the number of cycles it can endure throughout its lifespan.
For an in-depth analysis of premier battery storage systems, consult our best solar battery guide.
Join Thousands of Satisfied Customers:
We’re proud to be Tesla Certified Installers, MCS accredited and Which? Trusted installers with over 10,000 glowing reviews on Trustpilot. Discover why so many trust us for their solar panel & battery storage installations—visit our Reviews and Testimonials page and watch Phil’s video testimonial below.
Can You Add More Batteries Later?
If you like the idea of adding additional batteries at a later date, then it's important to opt for a battery brand that enables this.
Thankfully, most brands do, but brands differ a lot in terms of how many batteries you can add to the same series.
Inquiring about the required battery storage is merely one aspect to consider; various other factors hold significance when evaluating solar battery options, especially when considering serial connection:
Assess Maximum Capacity in Series: Ensure to check the maximum capacity permissible in series connection. Batteries have limitations, so it's crucial to ascertain the exact number. For instance, the Tesla Powerwall 2 offers the advantage of linking up to 10 batteries, yielding a collective capacity ranging from 135kWh to 140kWh.
Select Battery Chemistry, Manufacturer, and Model Thoughtfully: Exercise diligence in choosing the battery's chemistry, manufacturer, and model. Consistency is key; connecting batteries of the same type optimizes energy storage efficiency.
Verify Uniform Voltage Across Storage Systems: Consistency in voltage across storage systems is paramount for safety, longevity, and compatibility. Ensure that all batteries share the same voltage specifications.
Confirm Compatibility with Solar Panels: Some batteries are tailored to specific types of solar panels. Before making a purchase, verify compatibility to prevent potential compatibility issues. Additionally, be cautious of manufacturer restrictions; certain batteries may only function seamlessly within their proprietary systems. By considering these factors alongside your energy requirements, you can make a well-informed decision when selecting solar batteries for serial connection.
Explore a Battery Storage Case Study: Check out an insightful Q&A session featured in one of our detailed case studies on battery storage. Hear directly from a Heatable customer in the UK and gain valuable perspectives on their experience here.
The image above features a Tesla Powerwall 3 installation performed by our team of Tesla-certified installers at Heatable.
Next Steps For Your Battery Journey:
When planning to install battery storage for your home, there are several important factors to consider. Make sure to refer to the following guides to help you make informed decisions:
To dive deeper into these topics, head over to our advice section, check out our YouTube channel for informative videos, or read a customer case study to see how others have benefited from their battery installation.
Get a Quote for Battery Storage Today
Without boasting you should get your battery storage installed with us, here's why:
Thousands of Happy Customers: We boast an average score of 4.9 on Trustpilot, outperforming the market leader.
Which? Trusted Trader: Heatable is proudly recognised as a Which? Trusted Trader.
Tesla Certified Installer: Heatable is proudly certified and approved by Tesla to install the Powerwall.
MCS Accredited: Our accreditation by the Microgeneration Certification Scheme (MCS) ensures high-quality standards.
Consumer Protection: As members of the HIES consumer code, we provide 2-year deposit protection.
Flexible Payment Options: Choose from multiple payment methods, including finance options.
Fixed Price Guarantee: Enjoy transparency with no hidden costs.
Save Your Quote: You can save your quote and decide later.
Bespoke Battery Quote Tool: Find out which battery is ideal for your home, here.
